A dense Al/SiCp composite coating with high volume fraction(60%)of nano SiCp reinforcement was fabricated by cold spraying of ball-milled Al-60SiCp composite powder.The morphologies evolution of the Al-60SiCp composite powder during ball milling and the microstructure and microhardness of the cold-sprayed Al-60SiCp composite coating were investigated.The results show that Al particles undergone fracture deformation and nano SiC particles are uniformly distributed in soft Al matrix after ball milling.A dense Al-60SiCp composite coating can be fabricated by cold spraying of ball milled composite powder.Nano SiC particles in the cold-sprayed Al-60SiCp composites coating exhibit a reasonably uniform distribution.The Hv0.5 microhardness of the Al-60SiCp composite coating is reached up to(5.30±0.53)GPa due to the enhancement of SiC particles,compared to(0.34±0.03)GPa for the pure Al bulk.
Wang HongtaoJi GangchangChen XiaoBai XiaoboChen Qinyu
TiB_(2)–Ni coatings with different binder phase contents were sprayed on Q235 substrate by a high-velocity oxygen-fuel(HVOF)method using ball-milled powders.The microstructure,phase compositions,as well as thermal shock behavior,abrasive wear,and corrosion resistance to molten Al-12.07 wt%Si alloy performances of as-sprayed coatings were investigated.The results show that the three TiB_(2)–Ni coatings structure is dense with low porosity,and the main phase compositions of the coatings are TiB_(2) and Ni similar to those of original powder.The coatings that have superior performance of thermal shock resistance have good bond to the substrate with no change in thick-ness and microstructure of coatings.Meanwhile,the coat-ings also have good durability in the molten Al-12.07 wt%Si after 60-h immersion test.And the mass loss of Q235 steel is five times as much as that of TiB_(2)–50Ni coatings after abrasive wear test.
Xiao ChenHong-Tao WangGang-Chang JiXiao-Bo BaiWei Fu
In this paper,three kinds of cermet particles with different binder phase and content,namely WC-12Co,WC-17Co and Cr3C2-25NiCr were deposited on the Q235 low carbon steel and WC-12Co coating substrates to investigate the effect of binder phase content and substrate hardness on deposition behavior of cermet particle during cold spraying.The morphology of the deposited particles was examined by scanning electron microscopy(SEM)from the particle surface and cross-sections.It was found that with increasing substrate hardness,the deposition behavior of cermet particles transformed from completely embedding into substrate to partially flattening and even rebounding.Varying the Co content from 12 wt%to 17 wt% influenced significantly the deposition deformation behavior of the WC-Co particles,the higher Co content brought about a fuller flattening of WC-Co particles.However,Cr3C2-25NiCr particle exhibited the relatively lower flattening ratio and significant rebounding of Cr3C2 even with the highest binder phase content,which may be attributed to the bigger Cr3C2 size and weak bonding between Cr3C2 and NiCr.
Wang HongtaoJi GangchangChen XiaoChen QinyuBai Xiaobo
